Adolescence is a unique time in development-a period of rapid change in emotional, social and career/vocational domains. At the same time, rates of substance use (alcohol/tobacco/drug), risky sexual behavior, and suicidal behavior increase and peak in young adulthood, potentially compromising healthy psychosocial development. As bariatric surgery emerges as a viable treatment for adolescents with extreme obesity (BMI>40 kg/m2), it is critical to establish a comprehensive picture of the needs of these patients as they mature into young adulthood. Prior to surgery, adolescents with extreme obesity typically suffer from a range of weight-related medical and psychosocial comorbidities. Data from a nationally representative school-based sample indicated that adolescents with extreme obesity in engaged in many high-risk behaviors at comparable rates to healthy-weight peers, while also engaging in other behaviors in more dangerous ways (e.g., sexual activity in females while under the influence of alcohol/drugs, smoking in males before age 13). These risks, combined with the comorbidities associated with extreme obesity, illustrate the vulnerability of this subpopulation. The initial literature indicates that following bariatric surgry, adolescents experience improvements in physical and psychosocial health which have the potential to positively alter their life trajectory. However, some adolescents may encounter new or emerging risks, such as increases in substance use, risky sexual behavior (e.g., HIV-risk behaviors) and suicidal behavior that may threaten these improvements postoperatively. These are critical gaps in the literature currently being investigated by the PI and a multi- institutionl group of investigators through the Teen Longitudinal Assessment of Bariatric Surgery (Teen-LABS) consortium (U01 DK066568; PI: Inge), the PI's affiliated ancillary study TeenView (R01DK080020; PI: Zeller) and NIDA supplemental funds awarded to the consortium (TeenView2). Together, these landmark efforts represent the first prospective controlled observational studies to provide a foundation for the understanding of the impact of adolescent bariatric surgery on high-risk behaviors as well as the potential mediators/moderators of that pathway in the short term (1st two post-operative years). Our initial data suggest remarkably low rates of engagement in high-risk behaviors prior to surgery, with some high-risk behaviors appearing to increase to more normative levels at 24-months post-operatively. Of immediate importance, and the focus of the proposed study (TeenView3), is the longer-term (36, 48-month) observation of postoperative weight and psychosocial trajectories for adolescents during the transition to young adulthood, as well as a more comprehensive testing of relevant risk and protective factors affecting the pathway from bariatric surgery to engagement in high-risk behaviors. TeenView3 will provide critical information by identifying psychosocial risks and benefits which will define clinical decision-making and management for future adolescent patients.